In printing, treatment fluids may be applied for treating an ink on a substrate or for treating a substrate prior to receiving ink. Ink treatment may be, for example, to improve print quality by enhancing fixation of ink on the substrate or to protect ink on the substrate. Such a treatment may include, for example, a pre-treatment component (e.g., a fixer) or a post-treatment component (e.g., a coating).
For example, a pre-treatment may be applied on a portion of a substrate to enhance fixation (e.g., bonding and/or hardening) of an ink to be subsequently applied on that portion of the substrate. If the ink is deposited on the substrate via an ink fluid, fixation may be desired to address coalescence, bleed, feathering, or similar effects characterized by ink migration across a printed surface. In other examples, a post-treatment may be applied to ink already applied on the substrate. Such a post-treatment may be to provide a coating over ink deposited on the substrate.
Common methods for applying treatments on a substrate include roll coating, spray coating, manual application or treatment ejection, for example, through a jetting device. In an example of treatment application by a jetting device, a printing system may include a printhead including a treatment printhead unit for jetting a treatment fluid on a treatment substrate location.